Field of the Invention
The present invention relates to a water-based ink for ink-jet recording and an ink cartridge.
Description of the Related Art
For ink-jet recording, a water-based pigment ink for ink-jet recording in which a pigment is used as a colorant is conventionally used. Since the pigment is insoluble to water, a technique for dispersing the pigment stably in the water is required. As a method for dispersing the pigment in the water, a method using a resin for dispersing pigment (pigment dispersing resin) is known. For example, Japanese Patent Application Laid-open No. 2012-25880 proposes a water-based pigment ink containing a pigment, a pigment dispersing resin and water.
In the recent years, as the ink-jet recording is performed at a high speed, a water-based ink for ink-jet recording suitable for high speed-recording is used. The water-based pigment ink for ink-jet recording using the pigment dispersing resin, however, has such a problem that discharge of the ink becomes unstable as the number of sheets of paper or recording medium, etc., is increased. For example, the water-based pigment ink using the pigment dispersing resin has such a problem that any warping (bending or deflection) of recording and white void of pinhole shape occur during a continuous recording, which in turn makes the discharge of the ink be unstable. Further, the water-based pigment ink for ink-jet recording using the pigment dispersing resin is also required to have an improved re-dispersibility (re-dispersion property).
In view of the above situation, an object of the present teaching is to provide a water-based pigment ink for ink-jet recording which is capable of improving the discharging stability during continuous recording and which is also excellent in the re-dispersibility.